SSBC A-153 Front Drum to Disc Brake Conversion - Non Power - 71 Demon 340
Have you connected with SSBC? I have been using their products for 20 years and always found them responsive. Why look for rotors elsewhere when they should make this right?
Confirming the Kelsey Hayes set up uses a different spindle than drum brakes - that's the point of the SSBC set up, adding disk brakes while using the drum spindle and suspension components.